HexSim is a spatially-explicit, individual-based computer model designed for simulating terrestrial wildlife population dynamics and interactions. HexSim is modeling framework within which population models can be constructed. Users define the model structure, complexity, and data needs. Every HexSim function can be accessed through a sophisticated graphical user interface (GUI). HexSim makes use of spatial data sets to capture landscape structure, habitat quality, stressor distribution, and other types of information. HexSim’s design makes it ideal for exploring the cumulative impacts on wildlife populations resulting from multiple interacting stressors.